Display for remote receiver in a utility management system

ABSTRACT

A method and apparatus for monitoring and testing the operation and configuration of a remote receiver in a utility management system, such as a load management system or a cable television subscriber control system. The receivers are responsive to encoded command signals to perform utility control functions such as remove electrical loads from the electrical distribution system or connect a subscriber to the CATV system. The receiver retrieves status information pertaining to the receiver, and transmits the status information over a data communications link to a hand-held operator display unit. The operator display unit receives the transmitted status information, and displays the received status information to the operator on a display.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No.06/790,872, filed Oct. 24, 1985, now U.S. Pat. No. 4,780,910, patent onOct. 25, 1988, which is a continuation-in-part of application Ser. No.680,742, filed Dec. 12, 1984, now abandoned.

TECHNICAL FIELD

The present invention relates generally to utility management systems,and more particularly it relates to an improved status display for aremote receiver for controlling an electrical load in an electrical loadmanagement system or for controlling a subscriber control unit in acable television (CATV) system.

BACKGROUND

Utility management systems, for example electrical load managementsystems for allowing an electrical utility to control the load on theelectrical system, are known in the art. These systems operate to divertenergy requirements to minimize electrical blackouts or "brown-outs".For example, U.S. Pat. No. 4,190,800 to Kelly, Jr. et al., entitled"Electrical Load Management System", assigned to the same assignee asthe present invention, discloses an electrical load management systemwherein a central station monitors the use of electrical power, and whenpeak demand periods occur, transmits coded information by radio from acentral station to remote receivers mounted proximate the electricalloads. In this patent, the transmitted signal includes address andcommand information which is decoded at the receivers. Receivers whichhave been addressed pass command information over the distribution linesto the electrical loads, and thereby controls the operation of thecustomers' power consuming devices.

Other load management systems employ separate radio receivers at eachcustomer's location, rather than providing a receiver at thedistribution transformer as in the aforementioned U.S. patent. Examplesof this type system include the types DCU-1120, -1170, -1180, and -1190utility radio switches manufactured by Scientific-Atlanta, Inc.,Atlanta, Ga., and the type REMS-100 radio switch manufactured by GeneralElectric, King of Prussia, Pennsylvania. These systems incorporate an FMreceiver which can receive a transmittal up to about 25 miles from atransmitter site. The transmitter issues commands to temporarily removepower from a selected load. This self-contained receiver is typicallymounted on or immediately adjacent to the electrical loads undercontrol, and receives its power from the line that feeds the controlledloads. Switches, jumpers, or other means contained within the receiverconfigure the receiver to respond only to a particular address or set ofaddresses, so that different geographical areas, types of appliances, ornumbers of consumers may be separately controlled.

A particular problem with these separate remotely-controllable radioswitches for electrical load management, as well as with other types ofutility management receivers such as subscriber control units for CATVsystems, is testing of individual receivers for responsiveness. Inparticular, for effective load management, the utility must develop ahigh degree of certainty that selected electrical loads will be removedwhen the commands are transmitted. If certain receivers aremalfunctioning or are located in fringe reception areas wherein commandsignals may not reliably reach the receivers, there will be uncertaintywhether a given command to reduce a load in an emergency situation willremove enough of the load to prevent a brown-out or other potentiallymore serious power interruption.

In the above-described General Electric REMS-100 radio switch, anoptional light-emitting diode (LED) is provided for test purposes. Thereceiver is responsive to receipt of a particular transmitted testcommand to illuminate the LED, and as meters are manually read by theutility, the LED can be checked. This test function allows a check ofcorrect wiring of the receiver, correct operation of the receiver, and acheck on the radio signal, and remains on indefinitely until commandedoff or until loss of power, and provides no other indicating function.

A hand-held transmitter may be used for testing these receivers, butverifying the correct and reliable operation of the receiver requires acheck of the system signal propagation properties. Thus, sending testsignals from the central utility transmitter, with the responseindicated at each receiver site, is preferable for testing. However, theREMS-100 receiver only has one indicator light for a one-time test whichis verified later by the utility. There is also no provision for testingany function other than correct wiring and simple yes-or-no one-timereceipt of the particular test command by the receiver.

The particular REMS-100 load reduction receiver described above does,however, include a built-in volatile memory for maintaining an on-goingrecord of valid messages received. This record is reset to zero by aparticular predetermined incoming radio message, or upon power loss andrestoration. Statistical data related to the number of load sheddingcommands provided to a particular receiver may be counted and retainedin the volatile memory. This information is valuable in evaluatingsystem performance, fringe area performance, and expansion coverage.However, the counting of the stored messages in the volatile memoryentails opening of the receiver enclosure and placing an external probeon certain pins of the internal memory counter. Opening of the unitrequires removal of the utility security tags or seals, and results ininconvenience to meter readers who must first remove the security tag,open the enclosure, connect a reading device to the memory, remove theconnector after reading the memory contents, close the enclosure, andreplace the security tag. In addition to risking the integrity of thecircuitry by manual placement of a probe onto the pins of the circuits,this procedure involves the expenditure of a great amount of time,effort, and money in opening the box, reading the memory counter, andreplacing the security tag or seal.

Other types of utilities, for example cable television (CATV)distribution systems, also experience problems in testing the utilitymanagement receivers, for example subscriber control units, forresponsiveness or for operability. While these CATV systems typicallypossess certain limited communications capabilities, it is oftenimpossible to precisely determine information about the operation of thesubscriber control unit. For example, it is desirable to monitor whetheror not the subscriber control unit is operating, whether it is connectedor disconnected, how many subscriber modules are connected, whether thejamming oscillators provided therein for preventing receipt of undesiredprogramming is operative, the status of premium programming, the statusof power to the unit if the unit is home powered, or the security alarmstatus. Without physically inspecting the unit, and in some instancesphysically opening the enclosure to inspect the state of components orof connections therein, the above-mentioned and other types of statusinformation is not obtainable in prior art CATV systems.

Since many off-premise subscriber control units are mounted on utilitypoles, there are also concerns for the safety of CATV maintenance andinstallation personnel who must climb the poles to inspect the units, aswell as concerns over the productivity levels for CATV personnel whomust perform system audits by visiting sites. Productivity is affectedby factors such as weather and the need to provide a specialized buckettruck to allow access to the subscriber control unit.

Accordingly, there is a need for a method of testing or monitoringutility management system receivers quickly and inexpensively andwithout inconvenient procedures such as breaking security tags or seals,risking the physical integrity of the circuitry, climbing poles, usingbucket trucks, or adding costly or complex circuit components into thereceiver.

While data displays are known in the art, and could easily be providedat each receiver for displaying more comprehensive testing information,complex data displays such as digital LED or liquid-crystal informationdisplays are expensive and would require modifying the receiverenclosure so that the data display could be viewed from the exterior ofthe receiver enclosure.

SUMMARY OF THE INVENTION

The present invention overcomes these and other problems in monitoringand testing prior art utility management systems receivers by providingan improved method and apparatus for testing and monitoring theoperation and configuration of such receivers. In the preferred methodand embodiment, a utility employee such as a meter reader uses ahand-held display unit to display operational and testing data which istransmitted via an optical data link from the utility receiver.Advantageously, one embodiment of the present invention utilizes apreexisting light-emitting display at the receiver for communicatingmore extensive data concerning the testing and operational parameters ofa receiver to the hand-held display unit, which displays the informationto an operator.

In another embodiment, a preexisting local oscillator in the receivercircuitry is modified to take advantage of the stray RF transmissionsprovided by the oscillator. The data is transmitted via an RF radio linkfrom the receiver to the hand-held unit by modulating the localoscillator in the receiver.

Briefly described, the present invention comprises an improved statusdisplay method and apparatus for a utility management system receiver.An internal memory of the receiver control microcomputer is employed tostore status data related to a plurality of parameters of operation ortesting of the receiver. In one embodiment, a predetermined statusinquiry command signal transmitted from a hand-held display unit causesthe receiver to retrieve the stored status data from the memory. Theretrieved status data is then formatted into a communications format fora data link, and transmitted via the receivers's light-emitting displayor RF oscillator.

A transportable hand-held display and transmitter unit is responsive toreceive the transmitted status data, and to convert this received statusdata into a form readable by an operator of the hand-held unit.

Advantageously, the receiver in one embodiment of the present inventionallows the retrieval and display of status data without breaking orremoving the utility security seal or tag, since the data is transmittedthrough the preexisting light emitting devices, whose original functionwas only to provide an indication of the current status of the radioswitch, or through a preexisting local RF oscillator, whose originalfunction was only to aid in the demodulation of signals transmitted tothe receiver.

More particularly described, the present invention comprises a displayunit including a transmitter for transmitting a coded command signalhaving address and command information to a load management receiver.Each of the receivers includes means for decoding the command andaddress signals, and is responsive to the decoded command signals forcarrying out a utility function such as removing an electrical load fromthe electrical distribution system or disconnecting a CATV subscriber. Amemory in each of the receivers stores data related to the operation ofthe receiver, for example, the number of transmissions of apredetermined test command signal from the utility central transmitter,the time elapsed since power loss or receipt of a predetermined resetcommand, the number of load control functions commanded and provided bythe receiver within a predetermined time period, the number of channelsbeing scrambled, whether a security breach has occurred, the number ofsubscriber modules present, equipment failures, connect/disconnectstatus of subscribers, information on pay per view/impulse pay per view(PPV/IPPV), or the status of the home power supply.

In addition, information concerning the configuration of the receiver isprovided in the disclosed embodiment for display to the operator of thehand-held display unit. For example, programmed address information,cold load pick up information, relay time out periods, and otherprogrammed parameters are stored and transmitted to the display unit sothat the operator can observe the coded address for the particularreceiver being tested, the sequence of function provisions for a coldload pick up, and the delay time period before reconnection of a givenload to the distribution system.

In one embodiment, a predetermined status inquiry command signal fromthe display unit causes the receiver to retrieve the status data fromthe memory, and transmit the retrieved status data in a predeterminedcommunications format either on the light-emitting display or via the"transmitter" of the modified RF oscillator. In the preferredembodiment, the retrieved status data is automatically and/orrepetitively transmitted. Preferably, in applications where the statusinquiry command is employed, the display unit is small andtransportable, and transmits the status inquiry command signal at lowpower so as to stimulate only a single, near-by receiver. An opticallyresponsive circuit or an RF receiver tuned to the frequency of themodified local oscillator is provided in the display unit for receivingthe optically transmitted status data from the receiver. The receivedstatus data is then converted to a format for display to the operator ofthe transportable unit. In the preferred embodiment, the opticallyresponsive element on the transportable display unit is engaged with thelight-emitting display on the receiver to receive the transmitted statusdata within an extremely short period of time, typically less than 1/2second.

Accordingly, it is an object of the present invention to provide animproved utility management receiver monitoring and testing method.

It is another object of the present invention to provide a utilitymanagement system testing method which does not require breaking orremoval of the utility security tags or seals at the sites of utilitymanagement receivers, climbing poles, or using bucket trucks.

It is another object of the present invention to provide an improvedutility management receiver testing system which allows the display ofmore detailed information pertaining to the operation and configurationof the receiver.

It is another object of the present invention to provide a method fortesting a utility management receiver which does not require anyphysical modifications to the enclosure of the receiver, or the additionof expensive data display devices at each receiver.

It is another object of the present invention to provide a system fortesting a load management receiver which allows the monitoring of agreater number of parameters of operation of the receiver than prior artmethods, such as the number of operations of particular controlfunctions, the number of test functions, elapsed time, and configurationinformation.

It is another object of the present invention to provide a method andapparatus for testing the operation of a subscriber control unit in aCATV system which transmits status information about the operation ofconnected subscriber modules, such as whether or not the subscribercontrol unit is operative, the connect/disconnect status of each of aplurality of subscriber modules connected to the subscriber controlunit, the status of jamming oscillators, the status of premiumprogramming or pay per view configuration, home power status if thesubscriber control unit is home powered, or security alarm status.

It is another object of the present invention to provide a method andapparatus for improving the monitoring and testing of utility managementsystems by allowing greater productivity for utility personnel byobviating pole climbing and the use of bucket trucks.

These and other objects, features, and advantages of the presentinvention may be more clearly understood and appreciated from a reviewof the following detailed description of the disclosed embodiment and byreference to the appended drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a preferred embodiment of a portable transmitter anddisplay unit and its use with a preferred embodiment of the loadmanagement receiver of the present invention.

FIG. 2 illustrates the front of the transportable transmitter anddisplay unit shown in FIG. 1.

FIG. 3 is a block schematic diagram of a load management systemconstructed in accordance with the preferred embodiment of the presentinvention.

FIG. 4 is a schematic diagram of the timing and control circuit andother circuits in the transportable display unit illustrated in FIGS.1-3.

FIG. 5 is a schematic diagram of the optical receiver circuit in thepreferred embodiment of the transportable display unit.

FIG. 6 is a flow chart diagram of the microcomputer program of thepreferred embodiment of the transportable display unit.

FIG. 7 is a flow chart diagram of the microcomputer program for thepreferred embodiment of the load management receiver of the presentinvention.

FIG. 8 is a timing diagram of the Manchester code data communicationsformat employed in the preferred embodiment.

FIG. 9 is a schematic diagram of a typical RF receiver/demodulator whichhas been modified in accordance with a second embodiment of the presentinvention.

FIG. 10 is a schematic diagram of the modified local oscillator in theembodiment of FIG. 9.

FIG. 11 illustrates the location of an off-premise subscriber controlunit for a CATV distribution system incorporating the preferredembodiment of the present invention mounted on a utility pole.

FIG. 12 is a block schematic diagram of a CATV subscriber control unitconstructed in accordance with the preferred embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, in which like numerals indicate likeelements throughout the several figures, FIG. 1 illustrates anelectrical utility load management radio switch or receiver 10constructed in accordance with a first embodiment of the presentinvention, and a hand-held transportable display unit 12 for stimulatingthe receiver 10 to retrieve data pertaining to the operation of thereceiver. In the preferred embodiments, the receiver 10 is a typeDCU-1120, -1170, -1180, or -1190 radio switch manufactured byScientific-Atlanta, Inc., whose microcomputer program has been modifiedas disclosed herein. Those skilled in the art will understand that thistype load management receiver includes a highly sensitive FM radioreceiver 32 (FIG. 3) which can receive a radio transmittal up to 25miles or more from a transmitter site. Typically, the receiver 10 isconnected via wires 14 to the utility electrical power distributionsystem and to various electrical loads at a customer site.

The radio switch 10 is configurable to control up to four differentelectrically separate loads by a plurality of control means such asrelays or triac switches, so that different types of loads at theconsumer's location can be controlled. For example, air conditioners andother types of loads considered non-essential may be controlled by onerelay, while more essential electrical service for refrigerators and thelike may be controlled by another circuit. These four controlled loadsare frequently referred to as "control functions".

An electrical utility typically provides a security seal or tag 15 todiscourage and monitor tampering. The preferred receiver 10 includes aninternal memory counter for maintaining a record of messages received.In the prior art, in order to read the contents of this memory, thesecurity tag 15 must be removed, and unit opened to reveal a connector(not shown). An external probe is placed on the connector to read thememory contents. Needless to say, it is undesirable to require removaland replacement of the security tag in order to monitor and test theoperation of the receiver 10.

The receiver 10 shown in FIG. 1 further includes a light-emitting diode(LED) display 16 as an indicator of operation. In the usualconfiguration, a red LED is provided as an indication of provision ofcontrol function #1. Optionally, a green LED is provided in the receiverfor purposes of indicating a "PROP CHECK" test function. The PROP CHECKfunction consists of an individual, group, or all-call (scram) addressplus a test function command. The green test function LED lights withoutany load shedding occurring, and merely provides an indication that aparticular predetermined command has been transmitted and correctlyreceived and decoded by the receiver. Typically, a single message istransmitted by the utility on a certain day. As customer meters aremanually read by the utility, the PROP CHECK LED is checked forillumination. If the light is illuminated, it is an indication that theparticular receiver being checked has been correctly wired, and iscorrectly operating to receive commands via the radio link.

In the first preferred embodiment of the present invention, the LED 16is employed to optically transmit data pertaining to the operation ofthe receiver to the hand-held display unit 12.

Still referring to FIG. 1, the display unit 12, seen from the rear,comprises an optical receiver 20 which is operatively positioned overthe LED 16 when it is desired to read the status data from the receiver.A push button S1 on the top of the display unit 12 actuates a low-powertransmitter contained within the display unit to provide a predeterminedstatus inquiry command radio signal to the receiver, which is thenresponsive to retrieve stored status data and modulate the data to theLED 16. The light from the LED is received by the optical receiver 20,and then displayed to the operator of the display unit 12.

Referring now to FIG. 2, the front of the hand-held display unit 12 isillustrated. The display unit includes a digital data display 22 fordisplaying the information received from the receiver 10. Although itwill be understood that other types of status data may be provided, inthe disclosed embodiment, the parameters of operation tested andmonitored include the number of operations of each of the four controlfunctions, designated F1 through F4, the number of test signalsreceived, and the elapsed time since power loss or reset. It will beunderstood that while more or fewer parameters may be monitored, such asmore or fewer functions may be provided or tested by a receiver, thepreferred receiver employed in the disclosed embodiment provides fourcontrol functions, thereby allowing the removal or shedding of fourdifferent circuits from the electrical distribution system. Thus, itwill be appreciated that the data display 22 displays in digital Arabicnumerals the number of operations of each of the four control functions(F1-F4), the number of test signals received (TESTS), and the elapsedtime (TIME) since power loss or reset, in one consolidated, easy-to-readformat. It will thus be appreciated that a utility meter reader or otheroperator can retrieve the status data of a particular customer'sreceiver at the time the customer's meter is read, and the recordedstatus data compared to the number of function control commands or testcommands provided by the main utility transmitter, so that a morecomprehensive monitoring of the operation of the utility load managementsystem may be accomplished.

In addition, it is specifically contemplated that information concerningthe configuration of the receiver being addressed may also be providedfor display to the operator of the hand-held display unit. By causing areceiver to provide information about the configuration of itself fordisplay on the display unit, a meter reader or other operator canexamine the particular functional aspects of the receiver noninvasively.For example, programmed address information, cold load pick upinformation, relay time out periods, and other programmed parametersrelated to the receiver configuration may be stored and transmitted tothe display unit. This allows the operator to observe, respectively, theradio address code for the particular receiver being tested, thesequence of function provisions for a cold load pick up, and the delaytime period before reconnection of a given load to the distributionsystem after disconnection. This configuration information may bedisplayed on the data display 22 either by time multiplexing in thepredetermined display areas labelled "F1" through "F4", "TESTS", and"TIME" in FIGS. 2 or 3 or, alternatively, by providing a larger datadisplay with more area for display of information.

The display unit 12 further includes an audible buzzer or beeper 24 forproviding an audible signal to the operator, which will be described ingreater detail below.

Referring now to FIG. 3, the disclosed embodiments of the loadmanagement system receiver 10 and the transportable display unit 12 willbe described. The receiver 10 comprises an antenna 30 for receivingtransmitted radio messages from a main utility transmitter 31. Thestructure and operation of an exemplary electrical load managementsystem comprising a utility transmitter and a plurality of receivers forreceiving coded information by radio from the main utility transmitteris shown in U.S. Pat. No. 4,190,800 to Kelly, Jr. et al., assigned tothe same assignee as the present invention, the disclosure of which isincorporated herein by reference and made a part hereof. As described inthis patent, the transmitted signal from the main utility transmitter 31includes both address and command information which is decoded at eachof the receivers. Those receivers which have been addressed utilize thecommand information to selectively remove electrical loads from thedistribution system. The address information informs the customer of theexistence of a peak load condition and/or controls the operation of thepower consuming devices and/or electric meter connected to the receiver.

In the preferred embodiment of the present invention, as illustrated inFIG. 3, a radio frequency (RF) receiver/demodulator 32 receives theradio frequency command signal from the antenna 30 and is responsive todemodulate the transmitted command signals and provide the demodulatedsignals to a microcomputer 35. The microcomputer 35 is programmed torespond to command signals for the particular address for the particularreceiver to provide the commanded control function. The microcomputer 35provides control signals over lines 36 to an isolation and relay drivercircuit 40, which drives the coils K1-K4 of a relay circuit 41. As willbe understood by those skilled in the art, actuating the coils K1-K4 ofthe relay circuit 41 trips the contacts T1-T4, respectively, of therelay to connect or disconnect electrical loads Z1-Z4, respectively,from the AC electrical power distribution lines 42. Although not shownin FIG. 3, it will be understood that power for the receiver 10 may bedrawn by a transformer connected in parallel to the AC lines 42.

Microcomputer 35 also provides a control signal on line 44 to a statusdisplay driver circuit 45, which controls the illumination of LED 16. Asdescribed above, the receiver 10 is operative to illuminate the LED toprovide an indication that a control function is being provided(typically function #1, indicating actuation of relay contacts T1), orto illuminate an optional separate LED as an indication of receipt ofthe PROP CHECK test function.

Also illustrated in FIG. 3 in block diagram form are the components ofthe transportable display unit 12. The preferred embodiment of thedisplay unit 12 comprises a microcomputer 50 as the central controllerof the display unit. The microcomputer is connected to a low power FMradio frequency transmitter 51, which drives an antenna 52. Such FMtransmitter circuits are known in the art, and will not be describedfurther herein. However, it should be understood that the transmitter 51employed in the disclosed embodiment is operative to transmit apredetermined status inquiry command signal at low power, in order toensure that the display unit 12 only triggers display of the statusinformation from a receiver in close proximity. Those skilled in the artand familiar with the structure of the preferred receiver 10 willunderstand that the "status inquiry" command optimally comprises asignal such as the "all call" or "scram" address plus a particularpredetermined test function code.

The microcomputer 50 is further operative to control the data display22. In the preferred embodiment, the data display 22 comprises a typeLM016 liquid crystal display (LCD) manufactured by Hitachi America,Ltd., San Jose, Calif. Those skilled in the art will understand thatthis type LCD display includes electronics which enable it to receivedata in parallel eight-bit ASCII format, which is then internallymanipulated to create the digital Arabic numeral display as shown inFIGS. 2 and 3.

Microcomputer 50 is also connected to an optical receiver circuit 20,which is described in more detail in connection with FIG. 5. The opticalreceiver 20 is operative to receive optically transmitted data from theLED 16 of the receiver 10.

A timing and control circuit 55 is also operatively connected tomicrocomputer 50, and is operative to detect the actuation of pushbutton switch S1 to begin operation of the microcomputer 50. A batteryBT1 connected to the timing and control circuit 55 powers the displayunit 12.

Referring now to FIG. 4, the construction of the timing and controlcircuit 55 will be described in more detail. Actuation of the switch S1controls the provision of power to the other components in the displayunit, and causes the microcomputer 50 to begin execution of its program(the flow chart for the program of microcomputer 50 is illustrated inFIG. 6). When an operator depresses switch S1, ground potential isimposed at node 61 and provides a conduction path for capacitor C1 todischarge through resistor R1 and diode D1 to ground. Also, capacitor C2discharges. Capacitor C1 is normally held charged through resistors R1,R2 by the battery BT1, which in the preferred embodiment is aconventional nine volt battery. Capacitor C1, after discharging, isrecharged through resistor R2 at a time constant of about 30 seconds ormore, to power down the circuitry as will be described below.

When capacitor C1 is discharged, a low will occur at the input of aninverter circuit 62, whose output is connected through a resistor R3 tothe base of an NPN transistor Q1. Unless otherwise noted, all gates andthe like employed in the preferred embodiment are CMOS to limit powerconsumption. Transistor Q1 then begins conducting, and allows power tobe provided on line 63 to the POWER input of LCD display 22. The BIASinput of the display 22 is connected to the negative terminal of batteryBT1, while the display ground is connected to the ground of the timingand control circuit 55.

Diode D2 connected between the negative terminal of battery BT1 and theground plane of the timing and control circuitry 55 provides a negativepotential to the BIAS input of the display 22 of approximately 0.7 voltsbelow the ground potential of the timing and control circuit, whichthose skilled in the art will appreciate enhances the appearance of theliquid crystal display.

A zener diode D3 connected between the base of transistor Q1 and groundlimits the voltage appearing at the base of transistor Q1.

The low appearing at node 61 from actuation of switch S1 also causes alow-going pulse to occur at one input of a NAND-gate 65. The low on node61 is coupled to gate 65 through capacitor C3, which is quiescently heldhigh through resistor R4. The output of NAND-gate 65 is connected to oneinput of a second NAND-gate 66, whose output is provided to the otherinput of NAND-gate 65 to form a latching circuit or flip-flop 67 knownto those skilled in the art. The output of flip-flop 67 is provided online 71 through a resistor R6 to node 73 and the base of an NPNtransistor Q2. In the preferred embodiment, transistor Q2 is aDarlington transistor, the collector of which is connected to thenine-volt battery and the emitter of which is connected to the powersupply V_(cc) of the microcomputer 50. When a high appears at 71 whenflip-flop 67 sets, transistor Q2 conducts, and provides power to themicrocomputer.

The cathode of a 5.6 volt zener diode D3 is connected at a node 73between the base of transistor Q2 and the base of another NPN transistorQ3, and limits the voltage appearing at the base of Q2. A resistor R7 isconnected between the base of Q3, the anode of D3, and ground. As knownto those skilled in the art, the preferred CMOS circuitry employed inthe disclosed embodiment operates over a fairly wide voltage range, butthe microcomputer 50 employed in the preferred embodiment, a type 8748manufactured by Intel Corporation, Santa Clara, Calif., requires atleast five volts for reliable operation. In the event that battery BT1becomes weak so that the high provided at node 73 is insufficient tobreak down the zener, transistor Q3 will not conduct. Stated otherwise,so long as the voltage at 73 is sufficient to break down zener diode D3,the base of transistor Q3 will be biased, and Q3 will conduct.

The collector of transistor Q3 is connected to line 74, which isconnected to one of the inport ports, PORT 2, of the microcomputer 50,while the emitter is grounded. Thus, it will be appreciated that whentransistor Q3 is on, a low will appear on line 74 at the PORT 2 inputfor sensing battery operation. In the event the microcomputer programdetects a high on line 74, steps for signalling a "battery low"condition are executed.

The power-down operation of the microcomputer 50 is as follows. One ofthe data bus (DB) lines of microcomputer 50 is provided through aresistor R8 and capacitor C4 to the base of a NPN transistor Q4. Thecathode of a diode D4 is connected also to the base of transistor Q4.The emitter of transistor Q4 is grounded, while the collector is pulledup to nine volts through resistor R9 and is connected to the input of aninverter circuit 75. The output of inverter 75 is connected to theremaining input of NAND-gate 66, the reset input of the flip-flop 67.

The power to microcomputer 50 remains until one of two occurrences: (1)the microcomputer 50 powers itself down, or (2) an RC network times out.In the first situation, microcomputer 50 will shut itself down at theconclusion of its program (as indicated in FIG. 6). The microcomputerplaces a low on the data bus line DB, which turns transistor Q4 off.With Q4 not conducting, the input to inverter 75 is high, placing a lowat the input of the flip-flop 67, which drives the output of theflip-flop at line 71 low. If line 71 goes low, the bias from the base oftransistor Q2 will be removed, and turn off power to the microcomputer.

The other mechanism for powering down the microcomputer is as follows.When microcomputer 50 begins its operation, the data bus line DB isbrought high under program control, placing a bias at the base oftransistor Q4, turning the transistor on and placing a low at the inputof inverter 75. Those skilled in the art will understand that thisprovides a high to the input of the NAND-gate 66, which together with ahigh on line 71 keeps the flip-flop 67 set and transistor Q2 conducting.However, capacitor C4 will charge through resistor R8, and willsubsequently remove the bias from transistor Q4, causing the transistorto turn off. It will thus be appreciated that this resets the flip-flop67, and removes power from the microcomputer. In the preferredembodiment, the R8/C4 time constant, which is dependent on the beta oftransistor Q4, is about 1-2 seconds, which allows ample time for themicrocomputer to execute its program. It should also be noted that thepower supply to the input V_(cc) of microcomputer 50 is about fivevolts, due to the dual diode drops across the Darlington structure oftransistor Q2, the voltage drop across the zener diode D3, and thebase-emitter drop of transistor Q3.

In the preferred embodiment, microcomputer 50 is a type 8748 eight-bitmicrocomputer manufactured by Intel Corporation. It will be appreciatedby those skilled in the art that other types of microcomputer circuitscan be substituted for the microcomputer used in the preferredembodiment with equally satisfactory results. The type 8748 isparticularly suitable for use in the present invention because itincludes an ultraviolet-erasable programmable read-only memory forprogram storage, a 64×8 data memory, and an on-board timer/counter.Microcomputer 50 also includes a pair of bidirectional output ports,PORT 1 and PORT 2, which are eight-bit quasi-bidirectional data ports.

Still referring to FIG. 4, the eight lines of PORT 1 are provided to thedata input of the display 22. It will be appreciated by those skilled inthe art that the microcomputer 50 is operative to provide ASCII data tothe display 22.

One of the PORT 2 lines is provided to beeper 24, shown in FIG. 3. Itwill be appreciated that microcomputer 50 can provide an audible signalto an operator by providing a signal on the selected PORT 2 line.Another of the PORT 2 lines is provided to the transmitter 51. It willalso be appreciated that particular predetermined all-call or statusinquiry command signal may be provided in digital form to thetransmitter 51, which is responsive to transmit the encoded signal tothe receiver.

The optical receiver 20, illustrated in more detail in FIG. 5, isprovided to the T1 test input of the microcomputer 50, shown in FIG. 4.It will be appreciated that the microcomputer receives the transmittedsignals from the receiver 10 by monitoring the signal activity on thetest input T1.

Referring now to FIG. 5, the optical receiver circuit 20 comprises aphotoconductive cell 80 for detecting the light emitted by the LED 16(FIG. 3). In the preferred embodiment, the photoconductive cell 80 is acadmium sulfide photocell such as a type VT-721H manufactured by Vactec,Inc. of St. Louis, Mo. Those skilled in the art will appreciate that thepreferred photoconductive cell has a wide dynamic range for high speedswitching and operates satisfactorily in high ambient light.

The photoconductive cell 80 is biased by the five-volt power supply ofthe display unit 12, and voltage fluctuations caused by the detection oflight are coupled through a capacitor C10 and resistor R10 to theinverting input of an operational amplifier A1. Capacitor C10 ispreferably of a value to transmit the relatively high frequencies of thetransmitted data from the load management receiver and to block 60 Hzpower line interference which may be present. A feedback resistor R11connected between the output of amplifier A1 and the inverting inputprovides a gain of about 100. Those skilled in the art will understandthat the structure of amplifier A1 is conventional.

The output of amplifier A1 is provided through a resistor R12 to thebase of an NPN transistor Q5. Transistor Q5 and its related componentscomprise a conventional common-emitter amplifier stage. The emitter oftransistor Q5 is connected to ground through RC network R13, C13, whilethe collector is connected through resistor R14 to the five volt powersupply.

The collector of Q5 is also connected through resistors R15, R16 to theinverting and noninverting inputs, respectively, of an amplifier A2configured as a voltage comparator/Schmitt trigger. The output ofamplifier A2 is fed back through resistor R17 to the noninverting input.Those skilled in the art will understand that the preferredconfiguration for amplifier A2 is to square-up input signals provided toit through the transistor Q5.

The output of amplifier A2 is provided to the test input T1 of themicrocomputer 50 in FIG. 4.

In the preferred embodiment, the encoding scheme for data transmissionfrom the load management receiver 10 to the hand-held display unit 12 isa bi-phase encoding format such as a Manchester code which allowstransmission of a synchronized clock reference for the data to betransmitted together with the data. Inasmuch as bandwidth requirementsare not of particular concern in the present invention, other types ofencoding formats, such as frequency shift keying (FSK) or pulse widthmodulation (PWM), may also be used with equal sucess. The clockfrequency of the microcomputer 50 should be high enough to insure thatthe program loop which tests the test input T1 for a high or low canproperly detect and decode the Manchester code.

Turning now to FIGS. 6 and 7, the general operation of the circuitrycomprising the preferred embodiment will now be described. FIG. 6 is aflow chart diagram which illustrates a sequence of steps which may beembodied as a program for the microcomputer 50 in the display unit 12.Similarly, FIG. 7 is a flow chart diagram which illustrates a sequenceof steps which may be embodied as a program for the microcomputer 35 inthe load management receiver 10. Those skilled in the art will nowunderstand and appreciate that apparatus as described herein fortransmitting a predetermined status inquiry command signal from adisplay unit to a load management receiver, for causing the receiver totransmit encoded status data via a preexisting LED indicator, forreceiving the transmitted status data and decoding same, and fordisplaying the decoded information in a format for an operator, may beconstructed by circuits comprising digital and analog hardware, or by apreferred embodiment, as disclosed herein, using programmedmicrocomputers together with peripheral digital and analog circuitry.

It will be understood that the embodiment disclosed herein is merelyillustrative and that the functional equivalents of the microcomputers35, 50 may include other devices including digital hardware, firmware,or software, which are capable of performing the described functions andsequences in the present invention. It will be further appreciated thatthe microcomputers 35, 50 may be programmed to perform the stepsillustrated in FIGS. 6 and 7.

Starting first with FIG. 6, there will be described the sequence ofsteps for operation of the display unit 12. The first step taken in thesoftware for the microcomputer 50, shown at 100, is to start operationof the microcomputer 50. It should be understood that the operator ofthe display unit 12 will depress the switch S1, which causes power to beprovided to the microcomputer 50. Those skilled in the art willappreciate that when power is provided to microcomputers such as thetype 8748 employed in the preferred embodiment, a start-up or initializeroutine is executed, which initializes and clears registers and beginsoperation of the program. After these initializing routines, typicallytaken at step 100, the predetermined status inquiry command signal istransmitted at 101.

It should further be understood that in normal operation, and asillustrated in FIG. 1, the optical receiver 20 of the display unit 12 isplaced in close operative proximity to the LED 16 on the receiver 10which is to be monitored or tested. The switch S1 is then depressed, andthe optical receiver will then be conditioned to receive the opticallytransmitted data. This step is illustrated at 102 in FIG. 6.

At 103, the microcomputer executes a routine which attempts to decodethe received information, it being understood that a Manchester code isexpected in the preferred embodiment. It will be further understood thatformatting information such as a header, a data stream, and finally atrailer such as a cyclic redundancy check (CRC) or other check bitscheme is employed in the preferred embodiment to insure that valid datais received from a light source. In the event that an improper format isdetected by the microcomputer, the "NO" branch is followed to 104. Themicrocomputer 50 then causes the beeper 24 to emit a short single beepas an audible indication to the operator that for some reason valid datahas not been received. Normally, at this point in the program, after thestatus inquiry command has been transmitted, the microcomputer will beexpecting a properly encoded and formatted optically transmitted datastream, and if such a data stream is not detected, there is therebyprovided an indication of a malfunction or other improper operation.

In the event that the proper data format is detected, the "YES" branchfrom 103 is followed to 105. At 105, the header and trailer informationof the data is stripped, and the data received by the microcomputerseparated and formatted for display on the display 22. As describedabove, this entails converting the received data into ASCII format forthe display 22.

At 106, the microcomputer tests the PORT 2 input on line 74 to determineif the power supply battery is beginning to deteriorate. In the eventthat the power supply is detected as weak, the "YES" branch is followedto 107, and a single asterisk (*) is provided to the display 22 inaddition to the data as described below. This provides a visualindication to the operator that the battery requires replacement.

In the event that the power supply is deemed adequate, or after anasterisk is output to the display as a weak battery indicator, step 108is reached, and the now-formatted data is provided to the display 22. Inthe preferred embodiment, a series of three short beeps are alsoprovided as an audible indication that the data is available for viewingand recording.

After either steps 104 or 108, the microcomputer 50 then at 109 providesa signal on the data bus line DB to cause power to be removed from thecircuitry. The program then enters an endless loop, until power isremoved via flip-flop 67 and transistor Q2. Power remains connected tothe display 22 through transistor Q1 for a longer time period aspreviously described to allow observation of displayed data.

Referring now to FIG. 7, there will now be described the sequence ofsteps for the microcomputer 35 in the load management receiver 10. Asdescribed above in connection with FIG. 1, the microcomputer 35 isemployed as the central controller for driving the isolation and relaydrivers 40 to selectively remove loads from the electrical distributionsystem, to illuminate the LED 16, and to decode commands received fromthe RF receiver/demodulator 32. It should be understood that themicrocomputer 35 in the disclosed embodiment, provided in the type DCU1180 receiver, is preprogrammed to provide these decoding and controlfunctions. These functions will not be described herein. However, in thepreferred embodiment, the program for the microcomputer 35 is modifiedto make the microcomputer responsive to a particular predeterminedstatus inquiry command signal to modulate the LED 16 to transmitretrieved status data. Accordingly, it will be understood that theprogram for the microcomputer 35 is altered to perform the sequence ofsteps illustrated in FIG. 7.

For purposes of describing FIG. 7, it should be further understood thatthe program therein illustrated in flow chart form may be implemented asan interrupt routine, a subroutine, or as part of the normal programflow for the microcomputer 35. For the discussion which follows, it willbe assumed that the microcomputer 35 is normally operative to decode andexecute commands transmitted to it by the main utility transmitterduring normal operation, and to be responsive to execute certain of thesteps of FIG. 7 only upon detection of a predetermined status inquirycommand signal.

Starting at 120, after any initializing or stack-saving routinescommonly executed in microcomputer programming, the microcomputer 35 isresponsive to detect decoded digital signals being provided to it fromthe RF receiver/demodulator 32 (FIG. 3), at 121. The digital signalsprovided to the microcomputer are first compared to the preprogrammedaddress information at 122, to determine if the particular receiver unitis being addressed. If proper address information is not decoded, theprogram flow returns to 121, to await receipt of another RF command.

In the event that the microcomputer 35 detects that it is beingaddressed, the "YES" branch from 122 is followed to 123. At this step,the microcomputer is responsive to compute the cyclic redundancy check(CRC) data or other data integrity checking scheme. If a 124 theinformation received is improper, the program returns to 121. On theother hand, if the CRC is determined to be proper, the "YES" branch isfollowed to 129.

At 129, microcomputer 35 has now determined that it has been addressed,and that it has received a valid command due to the detection of a validCRC test. At 130, the command received is compared to a special statusinquiry command. If this command is not detected, microcomputer 35 thenwill execute the particular command received at 131, which will be oneof the normal control or command functions provided by the receiver 10in normal operation.

If the special status inquiry command signal has been received, however,then at 132 the microcomputer begins a sequence of steps which retrievesthe status information from memory and transmits it through the opticaldata link, since the special status inquiry command signal in normaloperation is only transmitted by a hand-held display unit 12. In orderto accomplish these tasks, the microcomputer at 132 first disables anytimers or other microcomputer features which might disrupt thecommunications transmission. At 133, the microcomputer retrieves frommemory the status information described above. It will be recalled thatin the preferred embodiment, this status information comprises thenumber of provisions of control functions F1-F4, a number of testtransmissions received by the receiver, and the elapsed time since powerloss or a provision of a reset command signal by the main utilitytransmitter. It will be understood that this status information has beenprestored in a register of the microcomputer 35, or in an auxiliarymemory provided for storage of this information.

After the status information has been retrieved, at 134 themicrocomputer formats the information in a predetermined communicationsformat receivable by the display unit 12. As those skilled in the artwill understand, optical communications links typically comprise apreamble or series of digital signals which allow synchronization by thedisplay unit 12 to receive the optically-transmitted data. In thepreferred embodiment, it will be recalled that a Manchester code isemployed, and that use of this or other bi-phase communications formatsrequires the transmission of a predetermined number of bits ofsynchronizing information.

In the disclosed embodiment, and as illustrated in FIG. 8, the preferredcommunications format comprises a preamble of a predetermined number ofpreamble bits, fifty in the disclosed embodiment, each preamble bithaving a bit of cycle time of 160 microseconds, followed by the data tobe displayed. The data following the preamble is transmitted at a bit orcycle time of 480 microseconds, and the first or "start" bit is always a"1". The preamble bits allow time to synchronize the microcomputer (thepreamble bits are thrown out), and to establish quiescent operatinglevels for the components in the optical receiver circuitry 20. As willbe understood by those skilled in the art, the Manchester codeillustrated in FIG. 8 is decoded by determining the presence or absenceof a transition within the 480 microsecond cycle time, with the absenceof a transition indicating a "1" and the presence of a transitionindicating a "0". It will of course be understood that in FIG. 8 a lowlevel indicates that LED 16 is not illuminated, while a high levelindicates that the LED is lit. In radio switches having more than oneLED, it will be further understood that a plurality of LEDs may besimultaneously modulated in parallel as described to obtain greaterlight output, and thus improve signal-to-noise ratios under somecircumstances.

After provision of the preamble, the microcomputer 35 at step 135transmits in serial fashion, in the above-described Manchester codeformat, the status information which has been previously retrieved.Also, at step 135, it should be understood that any CRC which may beadded as trailer is computed and transmitted as well, so that thedisplay unit 12 can verify receipt of the data.

At 136, the microcomputer 35 restarts the timer and restores any stackinformation which had been set aside prior to entry of the statusinquiry command routine described herein. Then, the program returns to120, or exits the interrupt or other subroutine employed to implementthe herein-described status information transmission routine.

In a second preferred embodiment of the present invention, advantage istaken of the RF energy radiating characteristics of preexistingcircuitry in the RF receiver/demodulator 32 in the receiver 10 toprovide an RF data link for transmission of the retrieved status data.Those skilled in the art will understand that many conventional receivercircuits employ local RF oscillators in the demodulator circuitry tofacilitate frequency conversion, and that stray RF signals emanatingfrom these local oscillators can be detected for distances as great asseveral hundred feet from the receiver. In the second embodiment,advantage is taken of this stray radiating capability to create an RFdata link for transmission of the status data from the receiver 10 tothe hand-held display unit 12. The display unit accordingly is adaptedsuch that the optical receiver 20 is replaced with an RFreceiver/demodulator tuned to the frequency of the local oscillator toreceive the data transmission.

Referring now in particular to FIG. 9, there will now be describedmodifications to the receiver/demodulator 32 employed in the receiver10. Typically, receiver circuits for use in receiver/demodulator 32 aredouble conversion type, the construction of which will be understood bythose skilled in the art. Of course, it will be understood that othertypes of receiver circuits which have local oscillators that producestray RF transmissions can also be employed with the modificationsdescribed herein.

In the receiver/demodulator 32 employed in the disclosed embodiment, thereceiving antenna 30 is connected to an RF amplifier 150, the output ofwhich is connected to a mixer 151. Also connected to the mixer 151 is afirst local oscillator 152 which oscillates at a frequency of RF-10.7MHz, where RF is the transmission frequency of the FM encoded commandsignals to the receiver. The output of the mixer 151 is then providedthrough a bandpass filter 155 to a second mixer 156, which mixes thesignal with the output of a second local oscillator 157, whichoscillates at a fixed frequency of 10.245 MHz. The output of the mixer156 is then filtered by bandpass filter 160. It will be appreciated thatthe resultant frequency difference from the output of the second mixer156 is 10.7-10.245=455 KHz, the standard AM intermediate frequency.Thus, bandpass filter 160 is preferably 455 KHz. The output of filter160 is provided to a detector stage 161, the output of which is thedigital data stream provided to the microcomputer 35.

Either the first oscillator 152 or the second oscillator 157 can bemodified as described herein to utilize the oscillator as an RF signalsource. Data from the microcomputer 35 is provided over a line 162 fromthe microcomputer to either the second local oscillator 157, oralternately to the first local oscillator 152 on line 162'.

It will also be understood that a separate dedicated third oscillator ortransmitter could be provided in the receiver 10 for the specificpurpose of providing an RF data link to the hand-held display unit 12.

FIG. 10 illustrates the modifications to a typical oscillator circuit152 or 157, so as to modulate the oscillator to transmit data from themicrocomputer to the display unit. First, it will be understood thatwithout the use of shielding techniques, oscillators in receivercircuits radiate RF energy even without provision of a transmittingantenna. In most applications, there is no need to be concerned with thestray RF signal provided by such oscillators since the signal strengthis only sufficient to be detected within a few hundred feet, andtypically the frequencies are such that consumer electronic equipmentwill not be affected undesirably.

The oscillator 152, 157 illustrated in FIG. 10 comprises an NPNtransistor Q5 as the active component, with a feedback path providedfrom the emitter through capacitor C5 to the base of the transistor Q5.Resistor R10 serves as a load resistor, while capacitor C6 filtershigher frequency components to ground.

A crystal X1 is connected between ground and the base of transistor Q5and is the prime frequency-determining component. A voltage dividercomprising resistors R12, R13 provide biasing for the base of transistorQ5. An LC network comprising tunable coil L1 and capacitor C7 connectedbetween the power rail and the collector of Q5 allows tuning of theoscillator's frequency.

The previously-described components constitute a conventional oscillatorcircuit. The modifications to FSK modulating the oscillator are enclosedwithin the dotted block 168. A varactor diode VC1 is connected betweenground and through a capacitor C8 to the base of transistor Q5. C8 isselected to limit the frequency "pull" of the circuit and preventoperation at frequencies substantially above the selected frequency.Varactor diode VC1 allows the capacitive loading on the crystal X1 to bevaried as a function of a control voltage.

The control voltage from the microcomputer is provided through aresistor R15 to the node between the varactor diode VC1 and thecapacitor C8, and provides either a high or low voltage level to varythe capacitive loading to the crystal X1, thereby causing the crystal tooscillate at one of two selected frequencies.

The first oscillator 152, if modified to serve as the "transmitter", iscommonly known as a "tripler" in that the circuit operates at threetimes the desired local oscillator frequency. The crystal X1 is selectedon the order of 47 MHz, and the output of transistor Q5 at the collectoris on the order of 141 MHz. The line 165 from the oscillator is theradiating element.

In the configuration illustrated, the radiated energy of the oscillatoris strongest at the fundamental frequency of the crystal, namely, 47MHz, and at related harmonics including 94 MHz and 141 MHz. It has beendiscovered that the signal strengths at the fundamental frequency andfirst two harmonics is sufficient for transmitting distances on theorder of a few hundred feet. Thus, preferably the FM receiver in thehand-held display unit 12 is responsive to signals at either 47, 94 or141 MHz.

In the case of the second or "fixed" local oscillator 157, which it willbe recalled operates at 10.245 MHz, the signal at the collector of Q5will be strongest at the fundamental frequency of the oscillator, thatis, 10.245 MHz. Accordingly, the receiver in the display unit should betuned to this frequency if the second oscillator is modified to serve asthe "transmitter" for the data link.

It will be appreciated that the modulation technique described in thecircuitry of FIGS. 9 and 10 is frequency-shifting (FSK) in that theoscillator 152, 157 is caused to shift between two frequencies, one ofwhich represents a digital "0" and one of which represents a digital"1". It will be further understood that other modulation techniques canalso be employed with equal success in the present invention, forexample, amplitude modulation, phase modulation, audio frequencyshifting (AFSK), or other techniques. However, it will be appreciatedthat the technique disclosed herein is particularly easy to implementsince few modifications to the oscillator circuitry are required, inthat only the components within the block 168 must be added to aconventional oscillator circuit in order to transform the oscillatorinto an FSK "transmitter".

Another alternative easy-to-implement modification to the oscillator152, 157 is shown in dotted relief in FIG. 10 and comprises the additionof a diode D5 to the base of transistor Q5 to transform the oscillatorinto a continuous wave (CW) modulator, that is, on/off gating. It willbe appreciated that by connecting the anode of the diode D5 to the baseof transistor Q5, and providing a low or a high at the cathode from themicrocomputer 35, the oscillator can be switched on or off to transmitdata.

It will also be understood that other techniques for data transmissionbetween the receiver 10 and the hand-held display unit 12 can beemployed with equal success, for example sonic or ultrasonic techniquescan be employed by connecting audible sound or ultrasonic transducers tobe driven by the microcomputer 35 in the receiver 10, and by providing acorresponding receiver in the hand-held display unit 12. In addition,magnetic coupling can be successfully employed, for example, byproviding a coil to create a time-varying electromagnetic field as the"transmitter", and a corresponding coil as the "receiver" in the displayunit to which the field is coupled.

It will therefore be understood that other techniques may be employed totransmit commands from the display unit 12 to the receiver 10, forexample, by substituting an optical, audio frequency, ultrasonicfrequency, or other energy transmission device for the RF transmitter51, and by providing a corresponding energy signal receiver circuit inthe receiver 10. The important consideration is the provision of abidirectional communications link between the display unit 12 and thereceiver/remotely controllable switch 10 so that the receiver can bestimulated to retrieve prestored status data and transmit same to thedisplay unit for display to the operator, without breaking or removingthe utility seal or tag and without subjecting the operator of thedisplay unit to electrical hazard through any hard-wiring techniques.

It should be specifically understood that some applications of thepresent invention will not require the use of the status inquiry commandsignal for stimulating the receiver 10 to transmit the retrieved statusdata. In many applications, the receiver 10 may be programmed tocontinuously and repetitively retrieve the status information andtransmit same to the display unit 12.

Turning next to FIG. 11, there is illustrated another embodiment of autility management receiver 10' configured for use in an outdoorsubscriber control unit for a CATV signal distribution system. Thoseskilled in the art will understand that outdoor CATV subscriber controlunits may be of several types, for example an "off-premise" subscribercontrol unit is typically mounted off the subscriber's premises such ason a utility pole, and an "on-premise" subscriber control unit istypically located on the subscriber's premises such as on the side ofthe house. As in the case of an electrical load management system, atransportable receiver/recorder 12' with an optical data link isemployed to receive the transmissions of the retrieved status data fromthe subscriber control unit/receiver 10', whether off-premise,on-premise, or otherwise.

In many CATV applications, the receiver 10' will often be mounted on autility pole 201 and will therefore be inaccessible to a utilityemployee on the ground except by use of a bucket truck, by using aladder, or by climbing the pole. Advantageously, the provision of statusdata from the subscriber control unit receiver 10' to the display unit12' obviates climbing the pole and use of a bucket truck.

Alternatively, it will be understood that the subscriber control unit10' may be mounted in a pedestal on the ground in some applications, oron the side of a subscriber's house for an on-premise unit. In casessuch as these, a hole is provided in the pedestal or enclosure (notillustrated) so that the optically-transmitted data can be transmittedto the display unit 10'.

Accordingly, it will be appreciated that there are thereby providedseveral advantages by use of the present invention: greater safety forCATV personnel (since no climbing or sitting in traffic in a buckettruck is required), and higher productivity for CATV personnel. Thehigher productivity results from several factors. A greater number ofsubscriber control units may be inspected per hour, since the timerequired to receive the status data is nominal. There are cost savingssince a bucket truck is not needed. If sufficient power levels areemployed in the optical data link so that the range of transmission issufficiently great, there may even be no need for an operator tophysically approach close to the subscriber control unit. It is alsopossible that the status information may be received from within avehicle on the ground; thus, inclement weather or inconvenient locationsor environments (such as bad dogs) will be not delay or prevent receiptand display of the status information.

It will also be understood that security of the subscriber control unit10' is of greater concern for on-premise subscriber control units, sincethe unit is more accessible to tampering. Accordingly, it will beappreciated that a security seal such as shown at 15 in FIG. 1 may alsobe employed for use in the subscriber control unit 10' to discourage andmonitor tampering. It will also be appreciated that the difficultiesencountered in units having such a security seal, and the advantagesprovided by the present invention, are the same for the CATV subscribercontrol 10' in FIG. 11 as for the receiver 10 in FIG. 1.

A conventionally constructed subscriber control unit is modified toincorporate the present invention by providing a diagnostic port foroptical data transmission which will download or transmit statusinformation from the subscriber control unit and, in one contemplatedembodiment, up to four subscriber modules which are connected to andcontrolled by the subscriber control unit. The diagnostic port on thesubscriber control unit is constructed as in the load managementreceiver application described above, with the provision of adata-transmitting LED 16' positioned behind a plastic lens or cover. Inthe preferred mode of operation, at predetermined time intervals, forexample every several seconds, the control computer in the subscribercontrol unit (corresponding to the microcomputer 35 in FIG. 3)automatically enters a routine wherein the status information isretrieved from memory, formatted, and transmitted via the LED 16', inthe manner described above in connection with the load managementreceiver.

As will be known to those skilled in the art, the function of ansubscriber control unit (OPSCU) such as shown at 10' is to control theservices provided by the cable system to a CATV subscriber. A subscribercontrol unit is addressable from a head end control computer(corresponding to the main utility transmitter 31 in FIG. 3), whichtransmits control signals via the CATV network, including addresscontrol information. Functions typically provided in a CATV subscribercontrol unit include but are not limited to the following functions:

1. The connection of subscribers for service or disconnection ofsubscribers who do not wish to continue service.

2. The control of service to multiple subscribers, for example four inone known prior art subscriber control unit.

3. The control of a pay per view/impulse pay per view (PPV/IPPV) type ofsubscriber service.

4. The jamming, scrambling, or trapping of the television signalcarriers for particular subscribers so as to prevent the receipt ofdisplayable signals by certain subscribers, for example subscribers whochoose not to receive certain premium channels or subscribers who arephysically connected to the network but who have not subscribed to theservice.

5. The detection of intrusion into the subscriber control unit or into asubscriber module by a signal pirate and taking corrective action inresponse thereto, for example, by disconnecting or jamming the serviceto the port wherein the pirated signal is being misappropriated.

In order to monitor the operation of the OPSCU unit 10' which carriesout some or all of the above utility management functions, it isnecessary to store status information related to the provision of suchfunctions, and provide means for transmitting and displaying same. Forexample:

1. The connection of subscribers for service or disconnection ofsubscribers who do not wish to continue service requires identificationof a particular subscriber module connected to the subscriber controlunit, as well as the number of and identification of any premiumchannels to be received by a particular subscriber.

2. The control of service to multiple subscribers requiresidentification of which subscriber module is connected to whichsubscriber.

3. The control of a pay per view/impulse pay per view (PPV/IPPV) type ofsubscriber service requires subscriber identification and timinginformation for billing purposes.

4. The jamming, scrambling, or trapping of the television signalcarriers for particular subscribers so as to prevent the receipt ofdisplayable signals by certain subscribers requires identification ofwhich channels are to be jammed, for which subscriber modules.

5. The detection of intrusion into the subscriber control unit or into asubscriber module by a signal pirate should be signalled to the utilityso that the corrective action can be taken or further, follow-up actioninstituted.

6. The status of the power supply to the subscriber control unit forhome-powered units.

7. The storage, retrieval, and formatting for transmission for displayof an output of status information to a CATV support worker.

In preferred CATV embodiments, the OPSCU unit 10' will be provided withmemory as in the case of the load management receiver described above,for storing predetermined status information such as the identificationand number of channels being provided to a particular subscriber, thenumber and identification of channels being trapped for particularsubscribers, whether or not a security breach has occurred, the numberof subscriber modules present and being controlled by the subscribercontrol unit, the occurrence of any equipment failures including totalfailure, the connect/disconnect status of subscribers to the CATVsystem, information regarding PPV/IPPV if implemented, and the status ofhome power supplies for subscriber control units which are powered bythe electrical systems of a particular subscriber.

As in the case of the load management receiver discussed above, theretrieved status information is transmitted serially and modulated in apredetermined communications format. The status information is stored innon-volatile memory in the subscriber control unit 10'. The stimulusthat causes the data stream to be transmitted in one embodiment is atimed pulse from the microprocessor controlling the subscriber controlunit (which corresponds to the microcomputer 35 in the receiver 10described above in connection with FIG. 3), or alternatively, thepredetermined status inquiry signal described above. For example, aradio transmission or optical signal from the display unit 12' can causethe retrieval and transmission of the stored information, in the mannerdescribed above in connection with the status inquiry command signal forthe load management receiver.

Embodiments which employ means for transmitting the status inquirycommand signal via either light pulses or radio waves will entailslightly more expense in that a photodetector and supporting circuitry(corresponding to the optical receiver 20 in FIG. 3) will be requiredfor the receiver 10', but such an embodiment conserves power since thereis no need to repetitively and continuously transmit the statusinformation. In addition, use of the status inquiry command to stimulatedata transfer allows faster access to the status information, since theCATV worker with the display unit need not wait until the predeterminedtime for next automatic transmission of the status information.

FIG. 12 illustrates an alternative embodiment for the transportabledisplay unit 12' specifically for use in CATV management applications.It is used by a CATV maintenance or installation technician to gatherthe status information and display same. The display unit 12' comprisesa lens 202 for focusing received optical energy onto an infraredwavelenth photodetector 80, which is a part of an optical receivercircuit 20' constructed as described above in connection with thereceiver 20 in FIG. 5. An infrared passing filter 203 eliminatesunwanted external light from the photodetector. The lens 202 is providedfor increasing the optical sensitivity of the receiver 20' and forovercoming the effect of any dirt accumulation on the housing of the LED16' in the subscriber control unit 10'. The lens and filter also allowsrejection of unwanted lights such as sunlight and light from streetlights.

The microprocessor 50, as in the load management receiver embodimentdescribed above, is responsive to signals provided by the receiver 20'to demodulate the transmitted status information from the communicationsformat. Alternatively, a separate decoder 205 may be employed fordemodulating and decoding the status information from the predeterminedcommunications format.

An input keypad 210 is connected to a port of the microprocessor 50 andallows the prompting of the device for formatting of data beingdisplayed on a display 22', which corresponds to the display 22 shownabove in FIG. 2. In addition, the input keypad 210 can be used to allowoperator input of the number of a particular control unit/receiver 10'being polled, in the case of no response or mistaken identity. Forexample, it will be understood that each of the subscriber control units10' is responsive to a predetermined address from the head end computer,and in embodiments which include provision for stimulation by a statusinquiry command, the particular address or a global or "scram" addressmay be employed to provide further stimulation to the subscriber controlunit 10' in the event that a malfunction is suspected.

A memory or storage device 212, comprising volatile or non-volatilememory circuits, is provided for storing retrieved status informationfor display, and for possible later downloading to another computersystem. In addition, a bulk storage device such as a cassette tape drive(not shown) may be provided for collection of large amounts of data frommany subscriber control units for later computer analysis andevaluation. An RS-232 port 216 is provided for the purpose of connectionfor downloading or to a bulk storage device.

The microcomputer 50 is optionally connected to an LED opticaltransmitter or a strobe unit 214 to allow transmission of opticalsignals for providing the status inquiry command to the subscribercontrol unit 10'. In such applications, the LED or strobe unit 214corresponds to the RF transmitter 51 described above in connection withFIG. 3 for transmission of the status inquiry command.

It will be appreciated that if a strobe unit is employed, the opticaldetector in the subscriber control unit 10' (which corresponds to thereceiver/demodulator 32 in FIG. 3) can be relatively "numb" or opticallyinsensitive so as to simplify the circuitry and make it less expensive.Construction of such a "numb" optical receiver is within the skill ofthe art, and will be understood to comprise an optical receiver which isresponsive to one or more intense flashes of light (but not to sunlightor other light sources) to cause the microcomputer 35 to enterappropriate routines for retrieving and transmitting the stored statusdata.

The preferred embodiments of the present invention have been disclosedby way of example and it will be understood that other modifications mayoccur to those skilled in the art without departing from the scope andthe spirit of the appended claims.

What is claimed is:
 1. In a utility management system, said systemincluding means for transmitting address signals for directing commandsto utility management receivers and coded command signals forcontrolling actions to be taken by an addressed one of said utilitymanagement receivers, an improved utility management receiver forcontrolling actions and for transmitting status data obtained duringoperation of said receiver for display, comprising:address decodingmeans responsive to said address signals for determining whether saidreceiver has been addressed to receive a command; means for decodingsaid coded command signals in response to said address decoding meansdetermining that said receiver has been addressed, said coded commandsignals including an utility function command; means responsive to saidutility function command for carrying out a utility function; memorymeans for storing said status data related to a plurality of parametersof operation of said receiver; means for retrieving said status data forsaid memory means; formatting means for arranging said retrieved statusdata in a predetermined communications format; data transmitting meansfor transmitting data in said communications format; and display controlmeans operative for causing said data transmitting means to transmitsaid retrieved status data in said communications format to an externallocation for display.
 2. The improved receiver of claim 1, wherein saidcoded command signals include a status inquiry command, and wherein saidstatus data retrieving means is responsive to said status inquirycommand for retrieving said status data from said memory means.
 3. Theimproved receiver of claim 1, wherein said utility is an electricalpower utility, and wherein said receiver is a load management receiver.4. The improved receiver of claim 3, wherein said utility function is aload reduction function, and wherein said load management receiver isoperative to disconnect an electrical load from said electrical powerutility in response to a load reduction command.
 5. The improvedreceiver of claim 1, wherein said utility is a cable television utility,and wherein said receiver is a subscriber control unit.
 6. The improvedreceiver of claim 5, wherein said utility function comprises a functionrelated to the operation of said subscriber control unit, including butnot limited to disconnecting a subscriber from said cable televisionutility, controlling a plurality of subscriber modules connected to saidsubscriber control unit, jamming carrier signals to prevent receipt oftelevision signals by a subscriber module, controlling a pay per viewmode of operation of a subscriber module, detecting an intrusion into asubscriber module or into said subscriber control unit by a signalpirate, or providing said retrieved status data for display to anoperator.
 7. The improved receiver of claim 5, wherein said status datacomprises data related to the operation of said subscriber control unit,including but not limited to the number or identification of channelsbeing scrambled for a particular subscriber, the number oridentification of subscriber modules presently being controlled by saidsubscriber control unit, whether or not a security breach has occurredat said subscriber control unit, the number or identification of anyequipment failures detected by said subscriber control unit, the numberor identification of any premium channels being received by a particularsubscriber, or billing information for operation of said subscribercontrol unit or a subscriber module in a pay per view mode.
 8. Thereceiver of claim 1, wherein said data transmitting means comprisesoptical data transmitting means.
 9. The receiver of claim 1, whereinsaid data transmitting means comprises radio frequency data transmittingmeans.
 10. In a utility management system, said system including meansfor communicating coded command signals for causing the execution of autility function and a remotely located receiver for executing saidutility function, said receiver including means for decoding said codedcommand signals and means responsive to decoded command signals forexecuting said utility function,an improved status display for saidreceiver, comprising: memory means for storing status data related to aparameter of operation of said receiver; means for retrieving saidstored status data from said memory means; formatting means forarranging said retrieved status data in a predetermined opticalcommunications format; optical data transmitting means for transmittingsaid retrieved status data in said predetermined optical communicationsformat; display control means operative for causing said optical datatransmitting means to transmit said retrieved status data in saidpredetermined optical communications format; an electrically independentfree standing portable display unit separate from said receiverincluding means for receiving status data transmitted by said opticaldata transmitting means; and means for displaying said received statusdata on a display associated with said portable display unit.
 11. Theimprovement of claim 10, wherein said coded command signals include apredetermined status inquiry command signal, further comprising meansassociated with said portable display unit for transmitting saidpredetermined status inquiry command signal to said receiver, andwherein said retrieving means is responsive to said predetermined statusinquiry command signal for retrieving said status data from said memorymeans.
 12. The improvement of claim 11, wherein said coded commandsignals comprise address data and command data, wherein each of saidreceivers is responsive to command data only for particularpredetermined address data, and wherein said predetermined statusinquiry command signal transmitted by said portable display unitcomprises universal address data, whereby each of a plurality of saidreceivers is responsive to said predetermined status inquiry commandsignal.
 13. The improvement of claim 10, wherein said utility is anelectrical power utility, and wherein said receiver is a load managementreceiver.
 14. The improvement of claim 13, wherein said utility functionis a load reduction function, and wherein said load management receiveris operative to disconnect an electrical load from said electrical powerutility in response to a load reduction command.
 15. The improvement ofclaim 10, wherein said utility is a cable television utility, andwherein said receiver is a subscriber control unit.
 16. The improvementof claim 15, wherein said utility function comprises a function relatedto the operation of said subscriber control unit, including but notlimited to disconnecting a subscriber from said cable televisionutility, controlling a plurality of subscriber modules connected to saidsubscriber control unit, jamming carrier signals to prevent receipt oftelevision signals by a subscriber module, controlling a pay per viewmode of operation of a subscriber module, detecting an intrusion into asubscriber module or into said subscriber control unit by a signalpirate, or providing said retrieved status data for display to anoperator.
 17. The improvement of claim 15, wherein said status datacomprises data related to the operation of said subscriber control unit,including but not limited to the number or identification of channelsbeing scrambled for a particular subscriber, the number oridentification of subscriber modules presently being controlled by saidsubscriber control unit, whether or not a security breach has occurredat said subscriber control unit or at a subscriber module, the number oridentification of any equipment failures detected by said subscribercontrol unit, the number or identification of any premium channels beingreceived by a particular subscriber, or billing information foroperation of said subscriber control unit or a subscriber module in apay per view mode.
 18. The improvement of claim 10, wherein saidportable display unit comprises:display unit optical receiver means forreceiving said formatted status data; and means for converting saidreceived formatted status data into a format for display to an operatoron said displaying means.
 19. In a method for controlling a utilitymanagement system, said system including means for communicating addresssignals for directing commands to particular utility managementreceivers and coded command signals, and remotely located receivers forexecuting utility management functions, a method of monitoring andtesting said receivers, comprising the steps of:decoding the addresssignals at the receiver for determining whether the receiver has beenaddressed to receive a command; executing a utility function in responseto a utility function command signal when the receiver is determined tohave been addressed to receive a command; providing a memory in thereceiver for storing a plurality of parameters of operation of thereceiver; storing in the memory status data related to a parameter ofoperation of the receiver in response to the execution of a command bythe receiver; retrieving the status data from the memory atpredetermined times; formatting the retrieved status data in a formatfor display on a display means; and displaying said formatted statusdata on the display means.
 20. The method of claim 19, furthercomprising the step of determining whether the coded command signalscorrespond to a utility function command or a status inquiry command,and wherein the step of retrieving said status data from said memory isexecuted in response to the status inquiry command.
 21. The method ofclaim 19, wherein the utility is an electrical power utility, andwherein the receiver is a load management receiver.
 22. The method ofclaim 21, wherein the utility function is a load reduction function, andwherein the load management receiver is operative to disconnect anelectrical load from the electrical power utility in response to a loadreduction command.
 23. The method of claim 19, wherein the utility is acable television utility, and wherein the receiver is a subscribercontrol unit.
 24. The method of claim 23, wherein the utility functioncomprises a function related to the operation of the subscriber controlunit, including but not limited to disconnecting a subscriber from thecable television utility, controlling a plurality of subscriber modulesconnected to the subscriber control unit, jamming carrier signals toprevent receipt of television signals by a subscriber module,controlling a pay per view mode of operation of a subscriber module,detecting an intrusion into a subscriber module or into the subscribercontrol unit by a signal pirate, or providing the retrieved status datafor display to an operator.
 25. The method of claim 23, wherein thestatus data comprises data related to the operation of the subscribercontrol unit, including but not limited to the number or identificationof channels being scrambled for a particular subscriber, the number oridentification of subscriber modules presently being controlled by thesubscriber control unit, whether or not a security breach has occurredat the subscriber control unit or at a subscriber module, the number oridentification of any equipment failures detected by the subscribercontrol unit, the number or identification of any premium channels beingreceived by a particular subscriber, or billing information foroperation of the subscriber control unit or a subscriber module in a payper view mode.
 26. The method of claim 19, wherein the steps offormatting the retrieved status data for display and displaying theformatted status data comprises the steps of:formatting the retrievedstatus data in a predetermined communications format; transmitting theformatted status data to a separate display unit with data transmittingmeans; receiving the formatted status data at the separate display unit;and displaying the status data on a display associated with the displayunit.
 27. The method of claim 26, wherein the step of transmitting theformatted status data comprises transmitting with optical datatransmitting means.
 28. In a utility management system, said systemincluding a remotely located receiver responsive to a transmitted codedcommand signal for executing a utility function, a receiver monitoringand testing apparatus, comprising:memory means associated with saidreceiver for storing status data related to a parameter of operation ofsaid receiver; means associated with said receiver for retrieving saidstatus data from said memory means; means associated with said receiverfor transmitting said retrieved status data in a predeterminedcommunications format; and a transportable display unit for displayingsaid status data to an operator, comprising: means for receiving saidtransmitted status data from said receiver transmitting means; a datadisplay associated with said transportable display unit and positionedfor viewing by said operator; means for converting said received statusdata into a format for display on said data display to an operator;means for displaying said formatted status data on said data display.29. The apparatus of claim 28, wherein said coded command signalsinclude a status inquiry command, and wherein said status dataretrieving means is responsive to said status inquiry command forretrieving said status data from said memory means.
 30. The apparatus ofclaim 28, wherein said utility is an electrical power utility, andwherein said receiver is a load management receiver.
 31. The apparatusof claim 30, wherein said utility function is a load reduction function,and wherein said load management receiver is operative to disconnect anelectrical load from said electrical power utility in response to a loadreduction command.
 32. The apparatus of claim 28, wherein said utilityis a cable television utility, and wherein said receiver is a subscribercontrol unit.
 33. The apparatus of claim 32, wherein said utilityfunction comprises a function related to the operation of saidsubscriber control unit, including but not limited to disconnecting asubscriber from said cable television utility, controlling a pluralityof subscriber modules connected to said subscriber control unit, jammingcarrier signals to prevent receipt of television signals by a subscribermodule, controlling a pay per view mode of operation of a subscribermodule, detecting an intrusion into a subscriber module or into saidsubscriber control unit by a signal pirate, or providing said retrievedstatus data for display to an operator.
 34. The apparatus of claim 32,wherein said status data comprises data related to the operation of saidsubscriber control unit, including but not limited to the number oridentification of channels being scrambled for a particular subscriber,the number or identification of subscriber modules presently beingcontrolled by said subscriber control unit, whether or not a securitybreach has occurred at said subscriber control unit, the number oridentification of any equipment failures detected by said subscribercontrol unit, the number or identification of any premium channels beingreceived by a particular subscriber, or billing information foroperation of said subscriber control unit or a subscriber module in apay per view mode.
 35. The apparatus of claim 28, wherein said receivertransmitting means comprises optical data transmitting means, and saidportable display unit receiving means comprises optical data receivingmeans.
 36. A transportable display apparatus for receiving statusinformation transmitted from a utility management system receiver anddisplaying same to an operator, said status information comprisinginformation related to a parameter of operation of said utilitymanagement system receiver, comprising:means for receiving status datatransmitted by said utility management system receiver; means forconverting said received status data into a format for display to anoperator; means for displaying to an operator a visual display of saidreceived status data; memory means for storing said received status datafor later recall; and output means for retrieving said received statusdata from said memory means and for providing said received status dataas an output.
 37. In a utility management system, said system includingmeans for communicating coded command signals for causing the executionof a utility function and a remotely located receiver for executing saidutility function, said receiver including means for decoding said codedcommand signals and means responsive to decoded command signals forexecuting said utility function,an improved status display for saidreceiver, comprising: said coded command signals including apredetermined status inquiry command signal; said coded command signalscomprising address data and command data; said receiver being responsiveto command data only for particular predetermined address data; memorymeans for storing status data related to a parameter of operation ofsaid receiver; means for retrieving said stored status data from saidmemory means in response to said predetermined status inquiry commandsignal; formatting means for arranging said retrieved status data in apredetermined optical communications format; optical data transmittingmeans for transmitting said retrieved status data in said predeterminedoptical communications format; display control means operative forcausing said optical data transmitting means to transmit said retrievedstatus data in said predetermined optical communications format; anelectrically independent portable display unit separate from saidreceiver including means for receiving status data transmitted by saidoptical data transmitting means; means associated with said portabledisplay unit for transmitting said predetermined status inquiry commandsignal to said receiver; said predetermined status inquiry commandsignal transmitted by said portable display unit comprising universaladdress data, each of a plurality of said receivers being responsive tosaid predetermined status inquiry command signal; and means fordisplaying said received status data on a display associated with saidportable display unit.
 38. The improvement of claim 37, wherein saidutility is an electrical power utility, and wherein said receiver is aload management receiver.
 39. The improvement of claim 38, wherein saidutility function is a load reduction function, and wherein said loadmanagement receiver is operative to disconnect an electrical load fromsaid electrical power utility in response to a load reduction command.40. The improvement of claim 37, wherein said utility is a cabletelevision utility, and wherein said receiver is an off-premisesubscriber control unit.
 41. The improvement of claim 40, wherein saidutility function comprises a function related to the operation of saidoff-premise subscriber control unit, including but not limited todisconnecting a subscriber from said cable television utility,controlling a plurality of subscriber modules connected to saidoff-premise subscriber control unit, jamming carrier signals to preventreceipt of television signals by a subscriber module, controlling a payper view mode of operation of a subscriber module, detecting anintrusion into a subscriber module or into said off-premise subscribercontrol unit by a signal pirate, or providing said retrieved status datafor display to an operator.
 42. The improvement of claim 40, whereinsaid status data comprises data related to the operation of saidoff-premise subscriber control unit, including but not limited to thenumber or identification of channels being scrambled for a particularsubscriber, the number or identification of subscriber modules presentlybeing controlled by said off-premise subscriber control unit, whether ornot a security breach has occurred at said off-premise subscribercontrol unit or at a subscriber module, the number or identification ofany equipment failures detected by said off-premise subscriber controlunit, the number or identification of any premium channels beingreceived by a particular subscriber, or billing information foroperation of said off-premise subscriber control unit or a subscribermodule in a pay per view mode.
 43. The improvement of claim 37, whereinsaid portable display unit comprises:display unit optical receiver meansfor receiving said formatted status data; and means for converting saidreceived formatted status data into a format for display to an operatoron said displaying means.